help please maths bounds question

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username4029770
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#1
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#1
David drove a distance(d) of 187km, to 3 sig.fig. He used 28 litres of petrol(p), to 2 sig.fig.
The petrol consumption(c)in km per litre is given by the formula: c= d/p
By considering bounds, work out the value of c, to a suitable degree of accuracy. You must show your working and give a reason for your answer
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CraigFowler
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#2
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(Original post by Mythsical)
David drove a distance(d) of 187km, to 3 sig.fig. He used 28 litres of petrol(p), to 2 sig.fig.
The petrol consumption(c)in km per litre is given by the formula: c= d/p
By considering bounds, work out the value of c, to a suitable degree of accuracy. You must show your working and give a reason for your answer
Simply do the calculation c = d / p, from the data given and then state the answer to the same degree of sf of the lowest data, e.g 2 sf
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Muttley79
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#3
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#3
(Original post by Mythsical)
David drove a distance(d) of 187km, to 3 sig.fig. He used 28 litres of petrol(p), to 2 sig.fig.
The petrol consumption(c)in km per litre is given by the formula: c= d/p
By considering bounds, work out the value of c, to a suitable degree of accuracy. You must show your working and give a reason for your answer
What's the smallest the consumption could be? Lower bound miles/upper bound fuel, then think about the largest ...
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Muttley79
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(Original post by CraigFowler)
Simply do the calculation c = d / p, from the data given and then state the answer to the same degree of sf of the lowest data, e.g 2 sf
This is not using bounds ...
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the bear
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#5
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#5
work out 2 values of c.... on using the upper bound of d & the lower bound of p

the other using the lower bound of d and the upper bound of p

suppose these came out as 6.34 and 6.32

then you could claim that c was 6.3

if however the values were 6.34 and 6.22 you could only say that c was 6
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CraigFowler
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#6
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#6
(Original post by Muttley79)
This is not using bounds ...
Agreed - i was being a bit thick, sorry
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timif2
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#7
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#7
The best way to think about bounds is applying it. Think of pizza. Case 1: Division - So think if you and your mates have a pizza the maximum amount of pizza would happen when you guys only eat a little bit of it, whereas the minimum would occur when you have a tiny amount of pizza and your mates eat AS much as possible. More formally, max A = max B/MinC it just means you have to leave as much as possible left over as dividing is breaking something down, so max/min means you don’t break it down that much you leave as much as possible.

The same goes for minimum values. You can use context in this example of fuel consumption. You want to have the MINIMUM fuel consumption as you can, because you’re saving money in a way, so you would do min/max (you divide by max because it’s the worst possible case scenario where you’re using the most amount of petrol (p)) try to actually think about the Qs and they become clearer
Last edited by timif2; 3 years ago
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Vinny C
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#8
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#8
Did he own a valid driving licence?
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sccheema
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#9
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#9
(Original post by Mythsical)
David drove a distance(d) of 187km, to 3 sig.fig. He used 28 litres of petrol(p), to 2 sig.fig.
The petrol consumption(c)in km per litre is given by the formula: c= d/p
By considering bounds, work out the value of c, to a suitable degree of accuracy. You must show your working and give a reason for your answer
The Value of C = 7
Lower Bound = 6.543859649
Upper Bound = 6.818181818
The upper and lower bounds both agree to this number of figures
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daniii_m
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#10
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#10
this is what I wrote and got all marks:
187: 186.5 ≤ d < 187.5
28: 27.5 ≤ p < 28.5
upper bound: 187.5/27.5 = 6.82
lower bound: 186.5/28.5 = 6.54
6.54 ≤ c < 6.82
c = 7 because the upper and lower bounds both agree to 7
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